sweet trolling, bro. Once again you answered a question that I did not actually ask. Try harder. Step 1: read the question.
Not trolling, your question is simply ill-conceived. There’s no point in asking how something works until it is demonstrated that it does work.
I’m skeptical but ok.
“…aren’t any better” implies that they work. I’m not asking if they are better than another type of interval. It’s a different question (a valid one, but not one I’m asking).
If it is simply: they don’t work, say that. But not working better than continuous efforts is not the same thing. It implies there is some level of efficacy. It’s also possible that they are effective but not for the reasons that we think. Or effective at something else (incorrect attribution).
It is very likely that I’ve done them and my MAP is a higher number after a block that included them. But of course it could’ve been the other stuff in that block too.
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She says you spend more time at 90-100% vo2max than with a classical interval bout. The system does not shut down in the short breaks, you basically get time at vo2max for free. Furthermore, she says it is not as taxing, hence you can do it more often (she says 3 times per week)
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sounds like you’ve read some of bonen’s stuff. Can you post relevant details? I’ve never been willing to pay! 
His conclusions seem to be opposite yours in some respects. I’m curious to know the details…unless you mean to say increase in monocarboxylate transport expression doesn’t increase lactate transport. That is also an interesting assertion…so if that is what you mean also please do tell!
In the podcast, she was talking about maintaining lower lactate levels during the intervals compared to longer intervals.
In metabolism, “clearance” is defined as the rate of disappearance of a substance divided by the concentration. It is an attempt to account for the effects of mass-action. To calculate it, you obviously need to know both the rate of disappearance and the concentration - unfortunately, when it comes to lactate measuring the former is not at all straightforward, and there are few experts in the field who actually believe any of the data that have been published.
It therefore follows that if you can’t really quantify lactate clearance, you can’t really know what might account for changes in it.
Well in that case, the answer is obvious: by increasing maximal cardiac output and/or arteriovenous O2 extraction (just like continuous intervals).
So when Bonen says:
“Exercise training can increase the expression of both MCT1 and MCT4 in human muscle, although the extent of this up-regulation may be related to the intensity of training.”
Which part of that is wrong and why?
“you can’t really quantify lactate clearance”
How did Bonen do it, then? Please explain so we can understand why his methodology is flawed.
If my blood lactate goes from 13.8 to 1.2…why is it wrong to say that lactate was cleared from the blood?
If my blood lactate goes from 1.2 to 13.8…why is it wrong to say that lactate concentration increased?
None of it. You just shouldn’t equate expression of a transporter protein with the rate of clearance of a substrate from the blood. Sure, it may provide the potential for greater clearance, but it’s not the same thing.
He didn’t. You’re conflating measurement of membrane transport in isolated vesicles with whole-body metabolism.
It’s not, but “cleared” and “rate of clearance” after different things.
Take the first example - suppose that reduction happened over a 60 minute period of rest following a VO2max test. Simplistically, you might think that means a rate of removal of (13.8 - 1.2 mmol per liter)/60 minutes = 0.21 mmol per liter per minute. However, that’s liters of blood, not the total volume of lactate distribution, and at the same time lactate was being removed, it was also being produced. You would therefore need to use tracer methods to determine the actual rate of clearance of lactate, but standard assumptions of tracer methods don’t apply to lactate, so…
Resurrecting this thread, simply because I’ve been looking into HIIT stuff and Billat’s name inevitably came up. I wondered if anyone had taken any of the interval models and run with them? If so, how did you find the results?
As an aside, I believe much of the confusion comes from the fact that runners and cyclists use the term ‘threshold’ differently. From hanging around runners, and looking at some of Seiler’s work, it seems that most runners (and I suspect Billat) use threshold to refer to half-marathon pace or a *touch * faster; it seems much closer to what most of us would consider hard tempo or sweetspot in cycling.
I can’t speak to the long term effects of the intervals Billat describes but I did experiment with a Moxy monitor to see the effect on muscle oxygen saturation
This was 4x6 minute intervals, one of each type of “VO2max”-style interval.
Series are power, w’ balance, HR, SMO2.
- 30:30s at ~130%/60% CP
- Continuous at 110% CP
- Hard start, difficult to quantify but 90sec very hard, slowly letting power drop, after 3min power <CP.
- 15:15 at ~120%/80% CP
Based on the SMO2 response, if you are aiming for a sustained high VO2 for the duration of the interval, 30:30s are probably the least effective, as the muscle reoxygenates very quickly if the recovery intensity is too low. 15:15s however maintain a low SMO2, partly due to the short recovery period and the slightly higher recovery intensity.
The hard start didn’t seem more effective in driving down SMO2 than the continuous intensity interval, however I could reduce the intensity by quite a lot (~85% CP) before SMO2 started increasing again.
IMO there probably isn’t too much benefit in doing very short intervals over longer continuous VO2max reps, unless you’re also wanting to improve something like repeatability etc. However if you do do short reps the recovery intensity is just as important as the work intensity to keep SMO2 low (and VO2 high?)
Some quick thoughts
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Massively helpful, thanks.
One for next year’s CX prep, probably.
That looks a cool bit of kit, btw.
EDIT: I wonder if the data would be the same for a full session of each type? If you fancy doing some self-experimentation/TR research… 
Nice graphic, thanks! The typical 30/15s or 40/20s intervals are missing, would be nice to see those and also very interesting if you would try one of the “Rattlesnake” workouts (and maybe one of the VO2max float set workouts).
Very nice!
The SmO2 & HR between 30/30 and 15/15s are consistent with some of the work from Rønnestad’s group and others looking at 30/15s. IIRC they also found 30-sec recoveries were a bit too long and allowed VO2 to decrease too far.
Can you calculate in GC what the total work (kJ) in each set was? I wonder how they compare. (excluding the ‘rest’ intervals in the intermittent HIIT). What was your perception of effort across the sets? Obviously probably increasing difficulty with fatigue across the session.
We’ve done a bit of pilot testing using SmO2 to estimate recovery: i.e. when to go again during intermittent HIIT, loosely as a ~5-10% increase, depending on the individual. Turned out it agreed pretty well with sensations - or at least a few of us learned to predict when NIRS was gonna tell us to go again based on sensations. Need to follow up on that. What was your experience with that? Do you find NIRS matches sensations or no?
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Unfortunately I was only borrowing the Moxy so I can’t do any more testing. I would think the 30:15s would be quite effective, probably slightly more than 40:20s. As long as you keep the power at a moderate level on the recovery, what that is exactly is hard to say, maybe above LT1? Another thing to study 
The kJ expended were surprisingly similar, all sets were 120 ±2 kJ
In terms of RPE, I wouldn’t say the SMO2 lines up with effort too closely. For example, the first few minutes of an interval don’t feel too strenuous however the SMO2 will drop to <10%, and stay there, within 10-20 seconds of beginning the rep
The continuous interval is definitely the hardest, the 15:15s are psychologically quite good because they’re so short. The hard start ones are interesting, because you can let the power drop quite substantially you can do a very long interval, I have used 2x10 minutes in the past and Billat has stretched them out to 14 minutes, which is quite a long time to be near VO2max but if you know you’re two and done it’s somehow mentally easier
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She was part of the team that followed the late Robert Marchand. I had heard of her (I’m from Grenoble); she has the proper build of a Grenobloise - dry, light, not so interested in personal appearance. Her CV is quite impressive for someone who knows the French system.
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